检索结果-内蒙古大学图书馆

Analysis of model parameters and Experimental Setup for Accurate Characterization of Ultrasound Phased Arrays Using a Low-Cost Sensor

引用

IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2025年 74卷

作者： Attivissimo, Filippo Adamo, Francesco De Palma, Luisa Di Nisio, Attilio Ragolia, Mattia Alessandro Lanzolla, Anna Maria Lucia Polytech Univ Bari Dept Elect & Informat Engn I-70125 Bari Italy

Ultrasound phased arrays (UPAs) are an emerging technology for contactless midair haptics and acoustic levitation, offering many advantages compared to other contactless methods. Accurate characterization of the airborne ultrasound field produced by UPAs is crucial for evaluating their performance. This article introduces a novel UPA design and investigates the feasibility of using a low-cost commercial piezoelectric transducer, i.e., the Murata MA40S4R, for its characterization, in contrast to very expensive microphones commonly employed in literature for testing. The characterization is conducted both on the Murata MA40S4R transducer and on the proposed UPA, analyzing the experimental setup, the fitting of model parameters, the effect of wave reflection, duty-cycle dependency, and different directivity patterns on system performance. The architecture of the proposed UPA, the measurement chain, and the measurement protocol are described to ensure an accurate characterization procedure, and the influence of model parameters and experimental setup on the accuracy of measured data is investigated. The performed tests show that experimental measurements closely match predicted data after optimizing the model parameters and setup, achieving a root-mean-square relative pressure error of 4.1% in the focal region. This research highlights the possibility of obtaining accurate ultrasound field measurements with a very low-cost sensor, paving the way for accessible UPAs characterization and development.

关键词： Transducers Ultrasonic imaging Ultrasonic variables measurement Acoustic measurements Accuracy Pressure measurement Solid modeling Haptic interfaces Frequency measurement Phased arrays Airborne ultrasound field embedded systems experimental setup analysis low-cost sensor measurement protocol model parameters testing ultrasound phased arrays (UPAs)

来源：评论

学校读者我要写书评

暂无评论

model parameters Versus Gas Pressure in Two Different Plasma Focus Devices Operated in Argon and Neon

引用

JOURNAL OF FUSION ENERGY 2012年第1期31卷 13-20页

作者： Al-Hawat, Sh. Akel, M. Lee, S. Saw, S. H. Atom Energy Commiss Dept Phys Damascus Syria Inst Plasma Focus Studies Chadstone Vic 3148 Australia INTI Int Univ Nilai 71800 Malaysia Nanyang Technol Univ Natl Inst Educ Singapore 637616 Singapore

For the plasma focus device AECS PF-2 operated in Ar and INTI PF in Ne, model parameters of mass and current in the axial phase of plasma focus were found by matching the measured and calculated current waveforms over a range of pressures. The results show a value of f(m) = 0.05 +/- A 0.01 over 0.2-1.2 Torr in Ar;and f(m) = 0.04 +/- A 0.01 over 0.7-4.1 Torr in Neon. The value of f(c) = 0.7 was fitted for all cases. Combining these results with those published for several other small machines it would appear that, where measured current waveforms are not available for example in designing new machines, a good compromise would be to take a guideline value of f(m) = 0.05 and f(c) = 0.7 for both Argon and Neon.

关键词： Lee model model parameters Plasma focus device Argon Neon

来源：评论

学校读者我要写书评

暂无评论

Adjustment of muscle mechanics model parameters to simulate dynamic contractions in older adults

引用

JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME 2003年第1期125卷 70-77页

作者： Thelen, DG Univ Wisconsin Dept Mech Engn Madison WI 53706 USA

The generation of muscle-actuated simulations that accurately represent the movement of old adults requires a model that accounts for changes in muscle properties that occur with aging. An objective of this study was to adjust the parameters of Hill-type musculo-tendon models to reflect nominal age-related changes in muscle mechanics that have been reported in the literature. A second objective was to determine whether using the parametric adjustments resulted in simulated dynamic ankle torque behavior similar to that seen in healthy old adults. The primary parameter adjustment involved decreasing maximum isometric muscle forces to account for the loss of muscle mass and specific strength with age. A review of the literature suggested the need for other modest adjustments that account for prolonged muscular deactivation, a reduction in maximum contraction velocity;greater passive muscle stiffness and increased normalized force capacity during lengthening contractions. With age-related changes incorporated, a musculo-tendon model was used to simulate isometric and isokinetic contractions of ankle plantarflexor and dorsiflexor muscles. The model predicted that ankle plantarflexion power output during 120 deg/s shortening contractions would be over 40% lower in old adults compared to healthy young adults. These power losses with age exceed the 30% loss in isometric strength assumed in the model but are comparable to 39-44% reductions in ankle power outputs measured in healthy old adults of approximately 70 years of age. Thus, accounting for age-related changes in muscle properties, other than decreased maximum isometric force, may be particularly important when simulating movements that require substantial power development.

关键词： .changes isometric Simulated plantar simulations age-related represent exion contractions Torque lengthening Old Adults adjustments model parameters Muscle Mechanics normalized

来源：评论

学校读者我要写书评

暂无评论

Sensitivity Analysis of Nonlinear model parameters in a Multilayer Root Zone

引用

JOURNAL OF HYDROLOGIC ENGINEERING 2014年第2期19卷 462-471页

作者： Kumar, R. Shankar, V. Jat, M. K. Natl Inst Technol Dept Civil Engn Hamirpur 177005 HP India Malaviya Natl Inst Technol Dept Civil Engn Jaipur 302017 Rajasthan India

A numerical model is developed for simulating soil moisture movement for a multilayer crop root zone in subtemperate-subhumid agro-climates. Water dynamics is used for a nonuniform root distribution pattern to compute the root extraction rate by plants in a moisturescarce environment. The root uptake function is incorporated in governing the soil-moisture equation. Sensitivity analysis (SA) has been carried out to evaluate the relative importance of model input parameters in predictions of moisture uptake by plants. The paper describes the results of sensitivity analysis of model parameters for a maize crop and their spatial dimension. An iterative procedure has been used for the sensitivity analysis. The model was run for a range of values (+/- 10% and +/- 5% from base value) of different model parameters to obtain plant moisture uptake. Results indicate the model is least sensitive to saturated moisture content (theta(s)), coefficient (n), field capacity (FC), and permanent wilting point (PWP). The model is sensitive to residual moisture content (theta(r)), root uptake model parameters (alpha) and (beta), and saturated hydraulic conductivity (K-s) since variation in these parameters has significant impact on model output. (C) 2014 American Society of Civil Engineers.

关键词： Sensitivity analysis model parameters Soil moisture Crops Irrigation Evapotranspiration

来源：评论

学校读者我要写书评

暂无评论

A least-squares minimization approach for model parameters estimate by using a new magnetic anomaly formula

引用

PURE AND APPLIED GEOPHYSICS 2016年第4期173卷 1265-1278页

作者： Abo-Ezz, E. R. Essa, K. S. Cairo Univ Fac Sci Dept Geophys PO 12613 Giza Egypt Prince Sattam bin Abdulaziz Univ Al Kharj Saudi Arabia

A new linear least-squares approach is proposed to interpret magnetic anomalies of the buried structures by using a new magnetic anomaly formula. This approach depends on solving different sets of algebraic linear equations in order to invert the depth (z), amplitude coefficient (K), and magnetization angle (theta) of buried structures using magnetic data. The utility and validity of the new proposed approach has been demonstrated through various reliable synthetic data sets with and without noise. In addition, the method has been applied to field data sets from USA and India. The best-fitted anomaly has been delineated by estimating the root-mean squared (rms). Judging satisfaction of this approach is done by comparing the obtained results with other available geological or geophysical information.

关键词： New magnetic anomaly formula a linear leastsquares model parameters rms

来源：评论

学校读者我要写书评

暂无评论

Analysis of Two Ultrafiltration Fouling models and Estimation of model parameters as a Function of Operational Conditions

引用

TRANSPORT IN POROUS MEDIA 2013年第2期99卷 391-411页

作者： Corbaton-Baguena, Maria-Jose Vincent-Vela, Maria-Cinta Alvarez-Blanco, Silvia Lora-Garcia, Jaime Univ Politecn Valencia Dept Chem & Nucl Engn Valencia 46022 Spain

This work analyses the measure of fit of experimental data of permeate flux decline with time for ultrafiltration experiments performed with polyethylene glycol aqueous solutions to two different ultrafiltration models. A feed solution of 5 kg/m of polyethylene glycol and a monotubular ceramic membrane of - were used in the experiments. The first model considered was developed by Ho and Zydney and it considers two different fouling mechanisms: pore blocking and gel layer formation. The second model was proposed by Yee et al. It is an exponential model that considers three stages: concentration polarization, molecule deposition on the membrane surface and long-term fouling. The results show that both models give very accurate predictions for the severe fouling conditions (high transmembrane pressures and low crossflow velocities). However, both models cannot explain the experimental results obtained for all the experimental conditions tested. An equation for Ho and Zydney's model parameters as a function of operating conditions was obtained by means of multiple regression analysis.

关键词： Fouling dynamics Ultrafiltration Flux decline Multiple regression analysis model parameters

来源：评论

学校读者我要写书评

暂无评论

Prediction uncertainty of conceptual rainfall-runoff models caused by problems in identifying model parameters and structure

引用

HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES 1999年第5期44卷 779-797页

作者： Uhlenbrook, S Seibert, J Leibundgut, C Rodhe, A Univ Freiburg Inst Hydrol D-79098 Freiburg Germany

The uncertainties arising from the problem of identifying a representative model structure and model parameters in a conceptual rainfall-runoff model were investigated. A conceptual model, the HBV model;was applied to the mountainous Brugga basin (39.9 km(2)) in the Black Forest, southwestern Germany. In a first step, a Monte Carlo procedure with randomly generated parameter sets was used for calibration. For a ten-year calibration period, different parameter sets resulted in an equally good correspondence between observed and simulated runoff. A few parameters were well defined (i.e, best parameter values were within small ranges), but for most parameters good simulations were found with values varying over wide ranges. In a second step, model variants with different numbers of elevation and landuse zones and various runoff generation conceptualizations were tested. In some cases, representation of more spatial variability gave better simulations in term of discharge. However, good results could be obtained with different and even unrealistic concepts. The computation of design floods and low flow predictions illustrated that the parameter uncertainty and the uncertainty of identifying a unique best model variant have implications for model predictions. The flow predictions varied considerably. The peak discharge of a flood with a probability of 0.01 year(-1), for instance, varied from 40 to almost 60 mm day(-1). It was concluded that model predictions, particularly in applied studies, should be given as ranges rather than as single values.

关键词： .identifying Earth Sciences model structure model parameters HBV equally calibration period Conceptual rainfall-runoff Brugga different parameter Prediction uncertainty model variants

来源：评论

学校读者我要写书评

暂无评论

AN EFFECTIVE APPROACH TO OBTAIN model parameters FOR BJTS AND FETS FROM DATA BOOKS

引用

IEEE TRANSACTIONS ON EDUCATION 1992年第2期35卷 164-169页

作者： NATARAJAN, S Department of Electrical Engineering Tennessee Technological University Cookeville TN USA

In this paper, we address the problem of obtaining the values of small signal parameters of the high frequency hybrid-pi models of BJT's and JFET's for a given set of bias conditions from the data-book values. We also show the methods of determining the "typical" values of the input parameters to be used in the model statements of circuit simulators, such as SPICE.

关键词： bipolar transistors input parameter circuit simulator SPICE JFET model parameters signal parameter 11-(2-fluoroethyl)estradiol small-signal parameters

来源：评论

学校读者我要写书评

暂无评论

Estimation of load model parameters for harmonic analysis

引用

ELECTRICAL ENGINEERING IN JAPAN 2008年第2期164卷 44-53页

作者： Hayashi, Yasuhiro Matsuki, Junya Kobayashi, Kenichi Kanao, Norikazu Univ Fukui Fukui Japan

In order to devise countermeasures for harmonic disturbances and harmonic suppression in power systems effectively, it is necessary to develop a harmonic analysis approach with high accuracy. The major harmonic analysis approach is to re-create harmonic distribution in a power system model by using a simulation method. However, in order to carry out high-accuracy estimation of the harmonic distribution using the simulation method, after creating a load model which consists of several parameters associated with the measured harmonic impedance, the optimal load model parameters must be determined. So far, appropriate load model parameters have been determined by trial and error. Therefore, a systematic approach to determine the optimal load model parameters is needed to estimate the measured harmonic impedance with high accuracy. In this paper, a determination method for the optimal load model parameters to estimate the measured harmonic impedance is proposed. The proposed method is based on Particle Swarm Optimization (PSO), which is one of the optimization methods using the concept of swarm intelligence. In order to check the validity of the proposed method, the load model parameters estimated by the proposed method are evaluated using test data and field data of Hokuriku Electric Power Co. (c) 2008 Wiley Periodicals, Inc.

关键词： harmonic analysis harmonic impedance load model model parameters optimization method PSO

来源：评论

学校读者我要写书评

暂无评论

Measurement and simulation validation of numerical model parameters of fresh concrete

引用

SCIENCE AND ENGINEERING OF COMPOSITE MATERIALS 2021年第1期28卷 437-452页

作者： Zhang, Ke Yu, Wenda Li, Dong Zou, Defang Zhang, Shiying Shenyang Jianzhu Univ Sch Mech Engn Shenyang Liaoning Peoples R China

In the numerical simulation of the macroscopic flow of the concrete, it can optimize the performance indicators of the screw conveyor and improve the uniformity of the material to be discharged in the batch production. The discrete element method is effective. The accuracy of physical parameters of this method is a key issue for the reliability of the simulation results of concrete. In this study, we measured the parameters describing the interaction between gravel, mortar, as well as between these two materials and the wall (steel). The experimentally determined parameters include the particle density, size, shape, coefficient of restitution, coefficients of static, and rolling friction. The cohesion coefficient of mortar particles for batch time was obtained by comparing the spread diameter and flow time in V-funnel experiments and simulation. After these calibration steps, the DEM parameters were validated by comparison of the mass flow rate and driving power by the batch production of screw conveying in simulations and experiments. The calculated results are proved to be close to the experimental data, which demonstrates that the measured DEM parameters are of sufficient accuracy to be used in the simulation of concrete flow performance (mass flow rate, energy consumption) in the screw conveyors.

关键词： discrete element method fresh concrete model parameters time-dependence calibration

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：